rust/tests/compile-fail/while_loop.rs

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#![feature(plugin)]
#![plugin(clippy)]
#![deny(while_let_loop, empty_loop, while_let_on_iterator)]
#![allow(dead_code, unused, cyclomatic_complexity)]
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fn main() {
let y = Some(true);
loop { //~ERROR
if let Some(_x) = y {
let _v = 1;
} else {
break
}
}
loop { // no error, break is not in else clause
if let Some(_x) = y {
let _v = 1;
}
break;
}
loop { //~ERROR
match y {
Some(_x) => true,
None => break
};
}
loop { //~ERROR
let x = match y {
Some(x) => x,
None => break
};
let _x = x;
let _str = "foo";
}
loop { //~ERROR
let x = match y {
Some(x) => x,
None => break,
};
{ let _a = "bar"; };
{ let _b = "foobar"; }
}
loop { // no error, else branch does something other than break
match y {
Some(_x) => true,
_ => {
let _z = 1;
break;
}
};
}
while let Some(x) = y { // no error, obviously
println!("{}", x);
}
let mut iter = 1..20;
while let Option::Some(x) = iter.next() { //~ERROR this loop could be written as a `for` loop
println!("{}", x);
}
let mut iter = 1..20;
while let Some(x) = iter.next() { //~ERROR this loop could be written as a `for` loop
println!("{}", x);
}
let mut iter = 1..20;
while let Some(_) = iter.next() {} //~ERROR this loop could be written as a `for` loop
let mut iter = 1..20;
while let None = iter.next() {} // this is fine (if nonsensical)
let mut iter = 1..20;
if let Some(x) = iter.next() { // also fine
println!("{}", x)
}
// the following shouldn't warn because it can't be written with a for loop
let mut iter = 1u32..20;
while let Some(x) = iter.next() {
println!("next: {:?}", iter.next())
}
// neither can this
let mut iter = 1u32..20;
while let Some(x) = iter.next() {
println!("next: {:?}", iter.next());
}
// or this
let mut iter = 1u32..20;
while let Some(x) = iter.next() {break;}
println!("Remaining iter {:?}", iter);
// or this
let mut iter = 1u32..20;
while let Some(x) = iter.next() {
iter = 1..20;
}
}
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// regression test (#360)
// this should not panic
// it's okay if further iterations of the lint
// cause this function to trigger it
fn no_panic<T>(slice: &[T]) {
let mut iter = slice.iter();
loop { //~ERROR
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let _ = match iter.next() {
Some(ele) => ele,
None => break
};
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loop {} //~ERROR empty `loop {}` detected.
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}
}